Yoshiya Kiryu, nicknamed Joshua, is a main character from The World Ends With You and Neku's partner during the second week. His history is a mystery when Neku first meets him, but it later becomes known at the end of the game. He has a snotty attitude, which Neku immediately doesn't like in him, but they have to work together nonetheless. His battle style is a little different from Neku's, first using ground attacks and then having the ability to levitate. In various fusion attacks, they work together to cause serious damage to opponents. For their second fusion, Neku covers the enemies in fire while Joshua covers them in ice. Underneath his arrogant attitude, he is wise and mature at heart, and was able to gain a trustable relationship with Neku.

When Joshua first meets Neku, he claims he was just like Neku, and didn't think anybody needed friends. However, this can be questioned, since Joshua is revealed to be the Composer of the game, and also much older than he physically appears. As shown in a flashback, he was much taller when talking in his original Composer form to Megumi Kitaniji, the Conductor, who leads the other Harrier Reapers and Support Reapers but serves the Composer. Before Neku's Reapers' Game, Sho Minamimoto already has a hate for Joshua, and wants to take the power and position of the Composer away from him. Meanwhile, Joshua is discussing what to do with Shibuya to Kitaniji. He claims he just wants to get rid of Shibuya. Kitaniji, who is rather close to Shibuya, however, vouches for it, and Joshua gives him a challenge. If Kitaniji can do something with Shibuya to make it better, Joshua won't erase Shibuya. And so, the Composer sets a timer on Kitaniji's hand for a month, and the game begins. Joshua scouts Shibuya for a worthy proxy to help him win the challenge and erase Shibuya. As him and Sho are on a heated gun chase, Joshua comes across Neku. Sho tries to shoot Joshua, but Joshua proves unstoppable with his powers, and stops the bullets from hitting him. Sho flees and Joshua is left with Neku. He shoots him, and Neku starts his game.